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[vikram.jeet]

Prestressed concrete :-

Permissible stresses are given in IRC 18 .

Permissible temporary stress -
Compressive  = 0.45*Fck
Tensile =(0.45*Fck)/10

Permissible stress during Service -
Compressive = 0.33 * Fck
Tensile = NIL

These are as per old version,, For latest pl see latest version

[vikram.jeet]

Sample calcs sheet - Three lanes bridge
Screen shot of sheet showing Working out of Vehicular live load BM s for Class A one lane,, Class A two lanes Class A three lanes, ,, Class 70R wheeled, Class 70 Tr tracked,,,  Class  A  plus Class 70R  (in two positions viz Class A near kerb  and Class 70 R near ketb) ) worked out at Middpan sec,, 1/4th span sec  using ILDs.

Similar ways    other sections like 1/8th span,, Face of end block to be done

Similarly SF calcs done working from ILDs for shears

[vikram.jeet]

Sample calculation sheet

Reaction factors for three Girder scheme

[vikram.jeet]

Few important calcs sheet are being shared (screen shots) :-
1 working out of BMs due to LLs
2 . Reaction factors

Above already shared

Will share further :-

3 Prestress calcs for  for one set of Tendons

3a) Sample cable profiling  x secs  
3b)  Sample cable profiling L sec
3c), 3d), 3e) calcls of prestress forces and moments

[vikram.jeet]

Sample calcs sheet

Shear force calcs due to LL

[vikram.jeet]

SAMPLE CALCS SHEET - PRESTRESSING

[vikram.jeet]

Sample calcs sheet - PRESTRESSING

[vikram.jeet]

SAMPLE CALCS SHEET - PRESTRESSING

[vikram.jeet]

SAMPLE CALCS SHEET 2  - PRESTRESSING

[vikram.jeet]

SAMPLE CALCS SHEET -3   - - PRESTRESSING

Please see that the upper  points of UTS  on Slip diagram graph were plottedbased on values from previous sheet accounting for friction losses

To arrive  at slip of 10mm ,, trial point (UTS value) is assumed and mirrored inside,  And slip is calculated,, if it works less than 10 mm,  the UTS value is assumed is further assumed lesser to have trial matching slip of 10 mm.

This sheet was always time consuming but interesting.

Once trial values of UTS AFTER SLIP OK,, the extension at jackinv end and jack pressures can be worked out for putting in drgs. ( Area of Jack and it's efficiency shall because per type of jack used)  In illustration s it is eft as Aj  and  efficiency taken 85percent  but  to be adopted as per jack type.